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Continuous aspiration mechanical thrombectomy feasible for PE

Indigo Mechanical Thrombectomy System (Penumbra)

The procedure resulted in a significant decrease in the Miller index of the treated sides after mechanical thrombectomy (mean 9.8±4.4), compared with before intervention (mean 15.0±5), with a mean reduction in the Miller index of 35.3% ± 15% (p<0.01)

Continuous aspiration mechanical thrombectomy, with the Indigo Mechanical Thrombectomy System (Penumbra), is a feasible and promising intervention for patients with sub-massive pulmonary embolism (PE) and a contraindication to thrombolysis, according a small cases series by researchers from Miami Cardiac & Vascular Institute, Baptist Hospital of Miami, Miami, FL.

The study, ‘Continuous Aspiration Mechanical Thrombectomy for the Management of Submassive Pulmonary Embolism: A Single-Center Experience’, published in the Journal of Vascular Surgery, sought to assess the feasibility of continuous aspiration mechanical thrombectomy in patients with submassive PE and a contraindication to in catheter-directed thrombolysis (CDT).

Patients included in the study presented with acute PE diagnosed by computed tomography (CT) angiography, normotensive, evidence of right heart strain (RV/LV ratio>1, troponin > 0.04ng/mL, or prohormone B-type natriuretic peptide >500pg/mL), had a contraindication to thrombolysis and were therefore tteated with continuous aspiration mechanical thrombectomy.

In total, six patients (three men and three women) were included in the study and the contraindications to thrombolysis included intraspinal surgery (n=2), invasive procedure <10 days prior (n=1), recent trauma (n=1), age>80 years (n=1) and had a high risk of bleeding owing to extensive metastatic disease (n=1).

The mean patient age was 62.7 years ±19 and the mean Pulmonary Embolism Severity Index score was 94.3±with two patients in class II, three patients in class III and one patient in class IV. All the patients received systemic anticoagulation with heparin with a partial thromboplastin time goal of 60–100 seconds at the time of diagnosis of PE, which was continued throughout the procedure.

Outcomes

Venous access was obtained using the standard technique with ultrasound guidance via the right femoral (n=4), left femoral (n=1) or right internal jugular (n=1) vein. Aspiration was performed until a decrease in systolic PA pressure was obtained on repeat pressure measurements. The mean fluoroscopy time was 27.3 minutes, the mean initial systolic PA pressure 58.2mm Hg±13 and the mean CT obstructive index on presentation CT angiography was 60.4%±12.

The researchers report acute technical success in all six cases, as per Society of Interventional Radiology (SIR) reporting standards definition. They reported a significant decrease in the Miller index of the treated sides after mechanical thrombectomy (mean 9.8±4.4), compared with before intervention (mean 15.0±5), with a mean reduction in the Miller index of 35.3% ± 15% (p<0.01).

Follow-up CT angiography revealed a significant decrease in the CT obstructive index of the treated sides after mechanical thrombectomy (mean 47.0%±14.5), with a mean relative reduction of 31.2%±6 (p<0.01). There was also a significant reduction in RV/LV ratio after mechanical thrombectomy on follow-up CT angiography (mean 1.1±0.2) compared with initial presentation CT angiography (mean 1.7±0.5, p<0.05).

The authors reported no procedural or periprocedural complications, and all patients were discharged in stable condition at a mean of 6.7 days ±2.5 after intervention.

Follow-up was available on five of six patients at a mean of 246 days, four patients were asymptomatic at last known follow-up with return to baseline functional status from before acute PE. One patient presented with persistent exercise intolerance at 42 days owing to a cardiac event before intervention, but the patient did not experience any further decline compared with his functional status before the acute PE event.

“Larger, prospective studies are required to determine the significance of blood loss during aspiration mechanical thrombectomy,” the authors concluded. “…This intervention has the potential to immediately decrease PA thrombus burden and alleviate right heart strain.”